A filling device according to the preamble of claim 1 is known, and the applicant has already been constructing and selling it under the name Exact Volume CE 87 for a number of years now. The device comprises endless conveyor chains on which a plurality of container holders are fastened. The endless chains convey the container holders along an imaginary looped conveyor track with the abovementioned bottom and top track sections. By driving the chains, the container holders are conveyed in succession along a container infeed mechanism, a decontamination station, a drying station, a filling station, a closing station and a container discharge mechanism. The infeed and discharge mechanisms and the plurality of workstations are all disposed along the top track section. The greater part of the filling device, including conveyor chains, drive unit with chain wheels and processing stations, is enclosed in a substantially sealing manner by a large housing, in other words with the exception of the container infeed mechanism and the container discharge mechanism. During operation, conditioned air is blown in at slightly positive pressure through a plurality of air infeed mechanisms in the top side of the housing. The slight positive pressure serves to prevent polluted ambient air from being able to flow inwards into the housing during the filling process, for example through the container infeed mechanism or container discharge mechanism.
A disadvantage in the case of this known device is that there is a risk of pollutants being released or finding their way inside the housing. Such pollutants in this case very soon extend over the entire processing line. Polluted particles may be released in particular in the case of the conveyor chains, the chain wheels and other moving parts of the conveyor system. If aseptic filling conditions are desired, the entire filling device inside the housing is treated with hydrogen peroxide before the actual filling process is started. During the filling process it is then difficult to keep all parts inside the housing sterile with sterile air. The shape and the size of the area around the processing line inside the housing do not permit this.